Don't Look Back
by Gracie O'Malley
Summary: Sadie finds a ghost story book in a curio shop on a distant planet. She thinks it'll be a fun read, but then strange things begin to happen back inside the TARDIS. COMPLETE Doctor/OC Sadie
1. The Curio Shop

**The Curio Shop**

The bell tinkled as the door opened. The store smelled musty and old. Shelves crammed with books and odd trinkets were all over the place, lining the walls and sitting in clusters all over the room. Strange bits of metal twisted into odd designs were hanging from the ceiling. The Doctor would have probably bumped his head on a few of them, but Sadie, having not been blessed with a very good height gene, was perfectly safe.

"Greetings, mortal," came the gravelly voice from behind the counter. Sadie jumped in surprise and then whirled around to see who had addressed her. Seated behind the counter on one side of the shop was an apparently very old creature. He had an orange-tinted, cone-shaped head, with a small tuft of gray hair sticking out from the very top. One red eye was staring uninterestedly at her, the other eye covered in a large blue patch. Whatever the creature was, he was round shaped, and Sadie imagined he would waddle rather than walk. All in all, he seemed exactly the type you'd find in a store such as this.

"Can I help ye find anythin'?"

"Oh, um, I don't think so," Sadie said, feeling a bit awkward. "I was just looking. But thanks." The clerk snorted gruffly, and said nothing more. Sadie began to walk slowly through the shop, examining the various knickknacks with great interest. Trinkets intrigued Sadie very much, since there seemed to be an endless supply of them in the universe. The Doctor seemed to have a certain fondness for them as well. She had accidently stumbled across an entire closet full of them once, while searching for the bathroom in the TARDIS. She'd have to drag him in here to see these particular knickknacks, she decided mentally, moving from those shelves over to the ones containing books.

Sadie loved books dearly. There were several libraries in the TARDIS, and when the Doctor would begin to tinker with his beloved ship, she would venture off to find one of them (after asking directions, of course, she was NOT getting lost again!).

She ran a finger down the spines of the books, glancing at each title. Thanks to the TARDIS' translation circuits, she was able to understand what each one said. There were plenty that looked like novels, especially romance novels. Some of them looked like they might be textbooks, and there were a few cookbooks scattered throughout. One book in particular caught Sadie's eye, and she tugged it from the shelf to give it a closer look.

'_Ghosts of the Earthen Planet' _ was the title. The cover was illustrated with a painting of the Earth, with a large pair of glowing yellow eyes staring from behind it. Sadie thought she saw the eyes blink, but she wasn't entirely sure. Partly because the cover spooked her a little, and partly out of curiosity, Sadie flipped the book over to see what was written on the back cover, but it was blank. There wasn't even an author listed anywhere.

"Like the looks of that one, do ye?" the clerk asked, making Sadie jump yet again. "That's a good 'un." Sadie nodded, still clutching the book.

"Where did it come from?" Sadie asked, checking the inside covers of the book. "There's no author, publisher, or anything listed." The clerk shrugged.

"No one rightly knows where it came from. 'S jes' been here, 's all." Sadie's interest was definitely peaked.

"Ever read it?"

"No, ain't read it, but've heard tales of people who have. Comes pretty highly recommended, from what I heard."

"Really…" Sadie flipped the book back over to look at the cover once again. The eyes seemed to bore into her, sending a cold chill down her spine. That settled it. She **had** to have this book. "I didn't see a price on it…could you tell me how much it is please?" Nevermind that she didn't have any money on her…she'd find a way to get this book.

"Ye ain't from 'round here, are ye?" the Clerk asked, giving her a knowing look.

"No, I'm travelling through with a friend…but how did you know?"

"Jes' have that look about ye." Sadie felt a bit awkward yet again.

"Um, yeah…so can you tell me how much the book costs?" The clerk grinned, showing a mouthful of rotten teeth. Sadie grimaced inwardly.

"'ll give it to ye fer a kiss." Now Sadie grimaced outwardly. The clerk laughed heartily. "Jes' kiddin' ye. Ye seem nice enough, and 'd think ye'd enjoy it. So 's yers."

"Really?!" Sadie exclaimed, her earlier disgust giving away to excitement. "Oh wow! Thank you so much!" She tucked the book safely inside her bag, and poked around the shop for a few more minutes before deciding to head back outside to find the Doctor. As soon as she left, a grimy, satisfied smile crept on the face of the clerk. Success at last, he thought.

Sadie made her way through the crowded street to find the Doctor. The planet they were visiting now was called Tekram, and could best be described as just one huge shopping destination. Nothing but streets lined with various shops, and in front of the shops, lining the sidewalks, were booths and tents full of vendors. You could find anything and everything here, the Doctor had told her. Sadie scanned the crowds, looking for the familiar face. After several minutes she started to get frustrated.

"It figures that on a planet where you can find anything and everything, _he_ would be the hardest to locate," she muttered. Finally, and somehow through the madness around her, she heard his voice. She followed it, and found him standing underneath a tent, arguing with the vendor.

"This is NOT an antique," he was saying. "I should know! It's only twenty years old!"

"It is, sir," the vendor replied. "We've begun going by Earth guidelines." The Doctor's eyes widened.

"You have got to be kidding me," he exclaimed. "Have you ever been to Earth? Do you realize how backward, how inane, how completely and utterly-" At this point, Sadie coughed loudly, alerting him to her presence. The Doctor immediately froze, and looked down at her. Sadie gave him a pointed look. "Right. Lovely antique you have there!" The Doctor spoke quickly and then steered Sadie in another direction. "So, find anything interesting?"

"Just a book," Sadie replied, making a mental note to have a discussion with him later about the vendor incident. "The clerk was awfully nice and he let me have it for free."

"Oh, that's nice! It's amazing, isn't it, how you can find good people anywhere in the universe?" The Doctor said, stuffing his hands in his pockets as he strolled along. Sadie knew the signs. He was getting ready to go off on a tangent, and the only thing she could do was just smile and nod as he jabbered on and on.


	2. Explosion

**Explosion**

Once inside the TARDIS, Sadie headed immediately for her room, mostly to have another look at her brand new book, but partly to get away from the Doctor, as well. He could talk for hours about positively nothing at all. Sometimes it wasn't so bad, but at times it nearly drove Sadie insane. She often wondered if he talked just to hear himself. It was a very likely possibility.

She headed down the hallways, navigating them almost expertly. Twice she took wrong turns and had to go back. But she was learning. After her experience of being lost that one time, she'd asked the Doctor to at least map out where the most important places were, but he'd laughed off the suggestion, telling her she'd learn her way around in no time. For the most part, he'd been right, but a map would have come in extremely handy.

Sadie finally reached her room, pushing the door closed behind her, brimming with excitement. She sat down cross-legged on the bed, her bag in front of her. She reached for it, and noticed her hands were slightly trembling. That made her laugh.

"Well, that settles it," she said to herself. "I'm officially the biggest nerd in all of nerd-dom, to be this excited over a _book_." She sighed and shook herself. "Get a grip, Sadie."

She undid the flap on her bag and reached inside, feeling around until her fingers hit on the cool, slick cover. She grasped the book and pulled it out onto her lap. She tossed the bag to the floor beside her bed. It landed on its side, contents spilling out. Sadie paid it no attention, however.

She ran her fingers over the cover of the book, once again noting how spectacularly creepy the cover was. The glowing eyes seemed even brighter now. She shivered, just like she had in the shop. She eagerly opened the book to the first page, which was marked "Introduction". Her eyes eagerly searched for the first line, but right as they found it, a loud sound from elsewhere in the TARDIS made her jump. The book fell from her hands and slammed closed, landing on the quilt covering her bed.

She reached for the book again, but just as her hand closed on it, the Doctor began to shout and curse loudly. Apparently something hadn't gone as planned. Which seemed to happen quite often, actually. Sadie sighed deeply and rolled off the bed.

"Better go see what's up," she said aloud, tugging at the bottom of her shirt before heading for the door. The book was left lying on the bed.

As soon as Sadie had left the room, the eyes on the cover began to glow brighter and brighter. A soft, gruff chuckle echoed around the room before a deep voice spoke.

"Next time."

Sadie made her way through the halls once again, finally reaching the console room. The Doctor was hopping around like a madman, still cursing. The console was shooting sparks wildly.

"What did you do?!" Sadie exclaimed, making sure to keep herself well away from the sparks.

"I don't know!" The Doctor replied. "But I can't seem to un-do it!"

"Well you'd better figure it out before you blow us to smithereens!"

"I'm trying!"

The Doctor pulled levers, flipped switches, smacked the console with a sledgehammer, and did all other sorts of things to try to stop the sparks. Finally, he found the right combination of movements and the sparks ceased.

"I swear, one of these days you're going to do something wrong and blow us to bits…or worse," Sadie remarked. The Doctor looked offended.

"Never. I know what I'm doing," he said, defensively. Sadie smirked.

"Sure you do," she answered, turning to head back out. "Try not to catch yourself on fire, okay?" The Doctor chose to ignore her. Sadie began making her way back to her room, anxious to begin reading her mysterious new book.


	3. oıʇıuı

**oıʇıuı**

Back in her room, Sadie sat herself back on her bed, cross-legged as before, the book sitting in front of her. She picked up the book once again, and flipped it to the first page yet again. This time, printed across the top of the page was the word "Beginning". Sadie frowned. She hadn't remembered that particular word being there before.

"That's weird," she remarked to herself. "I thought it said 'introduction'." She pondered for a moment, then shrugged. "Oh well, I guess I could have gotten it wrong before." She focused her attention back on the book and began to read. Her green eyes skimmed from line to line fairly quickly, eagerly taking in the words. When she reached the end of the page, she paused, giving the book a curious look.

"'This book is unlike any other you will ever come across in your lifetime. It is often said that books come alive…," she read aloud from the last paragraph on the page, slowing down as she reached the final words. "'But no one knows just how true it really is…'" She trailed off, feeling very strange, and perhaps even a little bit scared. She took a shaky breath and then tried to rationalize.

"It can't be," she told herself. "It's a ghost story book, for cryin' out loud! It's supposed to be all spooky and stuff. Someone was just really, really clever and thought up that opening to get everyone all scared and stuff before they started reading. Very smart, I must say." Despite her reasoning, she still felt a bit uncomfortable. She shook herself, trying to get rid of the feeling, and slowly turned the page.

'˙oıʇıuı ˙ǝs ǝp olǝɟ ʇǝɔɐı ɔıɥ ˙ɹoʇɐıʌ ʇɐǝʌɐɔ' was across the top of the page. Sadie quickly flipped the book over and tried to make out the words. Finding it a bit of a struggle, she reverted to what she'd always been taught at school – if you have trouble reading something, try reading it aloud. So that is what she did, sounding out each word phonetically as she went. As soon as the last word left her lips, the book in her hands began to quiver. Sadie gasped and dropped the book, which fell onto the bed, still open.

Tendrils of wispy black smoke began to emit from between the pages, quickly filling the small room. Sadie sat frozen on her bed, completely petrified. She knew she could get up and do something. Her entire mind was screaming at her to get up, to run, to call the Doctor, to do _anything_ but sit there on the bed and do nothing. But she just couldn't move.

As she watched, the smoke began to spin in a circle around the room, slowly picking up speed. Soon, a large black funnel of smoke was whirling in the air above Sadie's head. Her eyes were glued to it, still unable to do anything but just sit and stare. She began to tremble as she saw eyes begin to take shape from inside the funnel. The eyes began to glow yellow, and she heard a faint, maniacal chuckling. The sound of it made her skin absolutely crawl. The funnel began to spin faster, the laughter growing louder, and the eyes growing brighter. It began to move towards Sadie. It grew closer and closer, but yet she was still frozen where she was sitting. Everything within her was still screaming for her to do something, anything, but it was too late.

The funnel descended, covering Sadie completely with its black smoke. The laughter was louder than ever, coming from both outside and in.

All Sadie could do was scream.

* * *

The Doctor's head snapped up. Had he heard screaming? He'd been lost in thought, so he wasn't entirely sure if he had actually heard anything, or if he had simply imagined it.

"Best go check, just to be sure," he told himself, straightening up and heading for the door. It was probably nothing, but he didn't want to risk it. Sadie was most likely just watching one of those horror films she was so fond of. He didn't quite understand the attraction. She'd scream herself hoarse at some silly, pointless movie that had the most unbelievable plot, and get herself so worked up that she'd refuse to sleep for at least three days. He'd watched a few movies with her, but for some reason she always got annoyed when he figured out the ending before it was even half over. He didn't think he'd ever understand humans.

By this time, he had reached Sadie's room. He knocked lightly on the door.

"Sadie?" he called. "Everything alright?" He waited, listening. Nothing. He frowned. That wasn't like Sadie at all. He called again, reaching for the doorknob. It wouldn't turn. That definitely was odd. He listened again, and couldn't hear anything coming from inside. He pulled his sonic screwdriver from his pocket and held it to the knob. Before he could use it, however, the door was flung open from the inside.

Sadie, who had opened the door, didn't greet him. She didn't even look at him. She moved slowly to the other side of the room, her movements cautious and meticulous. The Doctor frowned. Something was wrong.

"Sadie," he began gently, unsure of how to approach the situation just yet. "Are you alright?" Sadie didn't acknowledge him. "Sadie…"

Her head turned slowly towards him, and the first thing he noticed was her eyes. Instead of their usual green, they were now glowing yellow.

"Hello, Doctor."


	4. The Book

**The Book**

_The darkness was everywhere. The only sound was that of screaming. Somewhere a voice in the dark was calling, begging for something. She instinctively wanted to help, but she was trapped. She tried to move, to feel through the blackness to gain a clue as to her location. Using that she might be able to find the source of the screaming. But she couldn't. She couldn't think, couldn't move, and couldn't escape. There was nothing but the screaming. It went on and on, without a hint of ever ceasing. She knew there were words being used, but her brain was so scrambled she couldn't make them out. She shut her eyes tightly, willing her brain to work. Slowly, the proverbial wheels began to turn, and the words became clear._

"_Doctor! Help me!"_

_The screams were her own. She couldn't help, because she herself was in need of help. What had happened? She couldn't remember. All she could remember were the screams._

* * *

"Hello Doctor."

The first thing he noticed was that the voice was different. The speaker still looked relatively the same, but there was no mistaking the difference in the voice. Gone was the smooth, Southern-tinged, easily excitable voice that he'd grown very accustomed to. It had been replaced by a cold, harsh, menacingly deeper tone. One that spoke volumes without ever saying a single word. It was the hollow voice of nightmares.

He swallowed, feeling a bit unsure of what to do next. He felt very angry, but he realized that showing it now would probably not be the best idea, since he didn't know what he was dealing with just yet. For now, he would do what he did best. Talk.

"Hello," he replied, trying to appear as calm and blasé as possible. "Who, or maybe I should say what, are you?"

The person who had once been Sadie smirked. "You know who I am. I travel with you, after all."

"No," The Doctor replied immediately. "I travel with Sadie. You're not Sadie."

"But I am!" The smirk widened, the yellow eyes glittering evilly. The voice took on an almost mocking tone. "My name is Sadie Mitchell, and I've been travelling with you ever since you saved my life at the Dance back home." A callous laugh echoed around the room.

The Doctor felt his anger growing and his patience diminishing rapidly. He didn't like to play games. "Tell me right now what you are, and what you're doing here," he requested forcefully, yet still calmly. He was given yet another smirk.

"None of that is important."

"It is to me."

There was another laugh.

"No, I think you would much rather know how it is I have so much information about your lovely little companion. And you as well…" There was a lengthy pause. The Doctor knew that he was being baited. Whatever was doing this wanted a reaction out of him. He remained silent, refusing to give it what it wanted. He was rewarded with a glaring frown. The yellow eyes tinged orange, and then faintly red.

"Have it your way then, Doctor." The voice was deeper, more menacing than before. A book that had been lying unnoticed on Sadie's bed rose into the air and flew across the room, hitting the Doctor square on the chest. He caught it before it hit the floor, and clasped it in both hands. He looked down to see the cover, and was met by a pair of eyes. Green eyes. The Doctor quickly opened the book, finding just three words on the first page.

'Doctor! Help me!'


	5. Cat and Mouse

**Cat and Mouse**

The Doctor stared at the printed words. Somehow, Sadie had become trapped inside the book. It made sense, of course. Whatever was inside the book had come out, and something had to take its place. That something was Sadie. But the logistics of the process were irrelevant. More words appeared on the page, and his eyes moved quickly to them.

'Please, Doctor, help me…I'm scared…'

He felt a deep pang of sympathy for her. He knew she was scared. To be perfectly honest, he was growing increasingly worried with the entire situation. Whatever this was, it had encroached upon his territory. Nothing like this was supposed to happen inside the TARDIS. If anything happened to Sadie, or his beloved ship…  
He could feel anger beginning to boil up inside of him, replacing the worry, but he managed to keep it in check. His eyes shot daggers into his once-companion. He was met once again with the same smirk. He wanted nothing more than to forcibly remove it, but that was out of the question.

He realized with horror that this was going to be extremely difficult. Even though the being in front of him was really no longer Sadie, it was still in her form, and he couldn't risk anything happening to it. He would have to be very, very careful.

"So, Doctor," it said, grinning, yellow eyes glittering with delight. "What do you plan to do now?"

"I believe I asked you a question that you've yet to answer," The Doctor replied calmly, still clutching the open book in his hands.

"I believe I did answer."

The Doctor glowered, beginning to lose his patience. "Tell me right now who you are, and what purpose you have for this?"

The being shrugged before responding. "I just want to have a little fun."

The Doctor stood silently for a moment, blinking in confusion. "Fun?" he asked. "You want to have fun?" He was answered with an emphatic nod. He sighed and tried yet again to gain an explanation. "I'm only going to ask you once more. _Why are you doing this_?" He waited, hoping to finally get an actual response from the creature. He was glaring still, as if that might aid his questioning. It seemed to have no effect on the person standing opposite him whatsoever. The glowing eyes were still twinkling with amusement. It was enough to nearly drive one insane. After a few moments of tense silence, it finally spoke.

"You know, it gets ever so lonely sitting day after day on a creaky old bookshelf, waiting for some unsuspecting little idiot to come along and set you free…" The smirk returned, the eyes taking on a pure evil stare as the voice continued. "She really is an idiot, isn't she, Doctor? I mean, any intelligent person, upon finding such a strange book and having it given to them for free, would have immediately been tipped off! No one in their right mind would have accepted. Really says a lot about who you've been travelling with, don't you think, Doctor?"

Any bit of control that the Doctor had on his anger was now gone. There was little he detested worse than having someone think of themselves as anything less than brilliant. Before he could make any sort of protest, however, the being spoke once again.

"Oh now, don't get all upset with me calling her an idiot. She herself knows it's the truth! If you don't believe me, just look for yourself!"

The Doctor turned his attention once more back to the book, finding new words on the page. He read them quickly, his face twisting into a frown.

"Oh, no…Sadie…no…"

* * *

_The screams had stopped, thankfully. There was still darkness, though. A thick, heavy darkness that made it almost too much trouble to breathe. How long could she last this way? She wasn't sure. All she was sure of was that she wanted out. _

_She could hear voices, somewhere in the distance. Very faint, but if she strained she could just make out what they were saying. One of them she knew. The other, she could only guess. _

_She listened to the conversation. It seemed to be going nowhere, from what she could tell. She could sense impatience, and even a hint of anger in one of the voices, the one she knew. He would help her. She knew he would. He had to, he just had to…_

_She moved closer to where she thought the voices were coming from, hoping to be able to hear them better. It worked, much to her surprise. She listened carefully, hoping to somehow gain a clue as to how she might be able to escape._

"_You know, it gets ever so lonely sitting day after day on a creaky old bookshelf, waiting for some unsuspecting little idiot to come along and set you free…She really is an idiot, isn't she, Doctor?" The words cut into her like a knife. _

_She really was an idiot, plain and simple. She should have known. She should have stayed with the Doctor on that planet, she should have stayed far away from that shop, she should have run screaming from that horrible book, she should have…_

_She should have. But she didn't. _

_Her eyes flooded with tears as she realized the horrible truth. _

"_It's true. It's all my fault…I'm such an idiot…"_


	6. Plan of Action

**Plan of Action**

The Doctor paced up and down the hallway outside of Sadie's room. The open book was sitting propped up against the doorframe. He would glance at it every so often, hoping to see that more words had appeared on the page. But they hadn't. Not yet, anyway. They would come. He knew they would. At least, he very much hoped they would.

He paused, staring at the closed door. Somewhere behind it was the being, still in Sadie's body. It was pointless, he had decided, to stand there, doing nothing. He needed a plan of action, and to form a plan of action, he needed to think. So, he'd slipped outside, sonic'ed the door, effectively locking it inside, giving himself the opportunity he needed.

Unfortunately, though he had the time, he didn't seem to have any sort of idea of what he should do. He sighed, looking back to the book once more. New words had appeared. He quickly picked the book up to read it, feeling a tiny bit of relief.

'Doctor? Are you still out there?'

The Doctor was slightly confused.

"Of course I am. Why wouldn't I be?" he asked, and then waited for a response.

'I didn't know if you'd still want to help an idiot like me. I figured you would have just chucked the book and "me" out into space by now.'

The Doctor frowned.

"Sadie Mitchell, you are **not** an idiot, and I want you to stop thinking that way right now!" he ordered. "You know very well I would never do anything like that to anyone, no matter what." He waited again. There was a brief pause before more words appeared on the page.

'…I guess you wouldn't.' She didn't seem to be entirely convinced. The Doctor thought for a minute.

"Sadie, who fixed the loose wire on my machine and stopped the Appalian from controlling the minds of all those people at the Dance?"

'That was me.'

"Exactly. And who stopped the Slihh from eating any more people on that horrible, horrible planet?"

'You said you'd never mention that ever again.' The Doctor grinned.

"Desperate times call for desperate measures," he replied. "Now, think about it. If you were really an idiot, could you have done those things, plus the countless other things you've done since you've been with me?"

'But what about that time-'

"Sadie," The Doctor interrupted, warningly.

'Okay, okay. I guess when you really think about it, I have helped out a lot…'

"Exactly!" The Doctor exclaimed, grinning once again. He was starting to feel better about the situation now that he'd successfully pulled Sadie out of her funk. "Now, I'm going to need your help in this, Sadie. We're going to have to work together. Is there any information you can give me on what this thing is?" He waited, watching the page. There was a fairly long pause before Sadie responded through the text.

'It's too foggy, I can't…I'm trying, I really am, but I can't make anything out. I think I'm too far away.'

"Too far away? From whatever it is that's inside your room?"

'Yeah.' The Doctor sighed.

"Then I guess we go back in."


	7. A Problem Arises

**A Problem Arises**

The Doctor stood outside the door, contemplating. The book that contained what was essentially his companion was held tightly against his chest and there was nothing that could make him loosen his grip. He wished there was another way than what they were about to do but try as he might; nothing usable came to mind. He had plenty of ideas; he never failed to have a plethora of those, but when the stigma of usable was brought into the equation, well, the number usually dwindled a bit.

He truly did not want to go back into that room. He'd faced many creatures in his time, but this one had him baffled to say the least. It had a very strange method of operating, and he didn't like it. No, he didn't like it at all.

The Doctor felt sure he could handle whatever was thrown at him, but Sadie was another story. He had successfully pulled her out of her 'woe-is-me' state of mind, but he also knew that she was still very susceptible to the creature's actions, and could easily fall back into the mindset if pressed. That, however, could be chalked up to her human brain, as they tended to be inclined towards gullibility at times. And of course, Sadie couldn't help having a human brain. He would just have to do what he could to keep Sadie from believing anything the creature said.

He took a deep breath, steeling himself before applying his screwdriver to the door, unlocking it. The Doctor twisted the knob and pushed the door open slowly. The creature was sitting cross-legged on Sadie's bed, facing the door. It was smiling and waved cheerily as he entered.

"I've missed you. Did you miss me as well?"

The Doctor's face never changed expression. "No."

A bigger grin spread across Sadie's features. It looked unnatural, and was fairly unnerving. "So…did you come up with a plan?" The Doctor didn't reply. "I know that was what you were out there doing. Unlike your little companion, _**I**_ am not stupid."

"Sadie is anything but stupid," The Doctor answered quickly. He pulled the book away from himself and flipped it open. "You know what to do, Sadie. You can do this."

The creature frowned. "She won't be able to find anything."

"We'll see about that." The Doctor's eyes scanned over the page, anxious to see something, anything from Sadie. He was sure that she'd be able to come up with something that would help.

'Doctor, I can't…I don't know…'

"Sadie, you can. Just try."

The creature rolled its eyes, crossing arms over chest. "Sadie, you can do it, I just _know_ you can," it said mockingly. "Just try real hard, click your heels together three times, and don't forget to clap if you believe in fairies." The creature slid from the bed, crossing the short distance to the Doctor. In one swift movement, the book was snatched from the Doctor's hands and tossed across the room. The Doctor immediately gave an exclamation and went after the book, but a strong hand held him back. The creature was inhabiting Sadie's body, but the strength was definitely its own.

"You're making some very dangerous decisions," the Doctor warned. The creature didn't move.

"This whole procedure is useless," it said. "That moronic excuse for a human won't be able to tell you anything. Instead, why don't I just tell you what you'd like to know?"

"And you couldn't do this earlier because…?"  
"I didn't want to then."

"Right." The Doctor ran a hand through his hair, sighing. He cast a glance over to the floor, where the book had fallen. He supposed it would be fine, for now. He had a chance to find out some information, and he hated to let it pass by. At least this way, the focus would be off of Sadie. "So, first of all, who, or what, are you?"

"I am a Skeeva."

"A Skeeva?!" The Doctor exclaimed. "I thought your kind died out centuries ago!"

"Many of them did. But a select few have survived. We wrapped ourselves in the printed page for protection. No one ever suspects a book, you know. That also got us access to different planets. The demand for books from other solar systems is very high. From there, it was fairly simple."

"You just wait for some unsuspecting bookworm to come along and let you out," The Doctor said, finally able to put the pieces together. "Then, whoever was unfortunate enough to do so is then trapped inside the book."

"Exactly," the creature replied. "So, now that we've got it all clear, if you'd be kind enough to drop me off at the next planet, I'll just-"

"Whoa, there," The Doctor interrupted. "That's not going to happen. If you think I'm going to just let you walk off my ship inhabiting my friend's body, you're sadly mistaken."

The creature's eyes darkened, changing from a bright yellow to a burnt orange.

"This could be a problem."


	8. Yakety Yak

**Yakety-Yak**

"I see no problem." The Doctor was standing with his arms crossed, facing the Skeeva. He was wearing a grim expression. "Take yourself out of Sadie, go back into the book, and things will be peachy."

The Skeeva snorted. "You really must think I'm stupid, Doctor," it said. "I mean, seriously, you think I'm just going to roll over and do exactly as you say? Please. What gives you the right to boss me around that way?" The Doctor's eyes flashed with a hint of fury, but only briefly. Somehow, he managed to contain it. He spoke firmly and calmly, yet with evident underlying outrage.

"I'm a Time Lord. No one gives me authority. I **am** the authority."

The Skeeva blinked, momentarily taken aback. It obviously hadn't quite known who exactly it was dealing with until that very moment. The Skeeva recovered quickly, realizing it was far too late to go back now, and began emitting a low sound, eyes flashing nearly red. The Doctor listened closely for a moment before giving a look of surprise.

"Are you…growling?" he asked incredulously. The sound grew louder. The Doctor felt a wave of relief. Finally, something he could work with. His nimble brain quickly devised a plan that hinged upon his strength – talking. He stuffed his hands in his pockets before beginning. "Really now, that's just wrong. Such a basic animalistic expression, growling. I would have expected much different from a Skeeva. But I suppose being trapped in a book for centuries or so would cause you to revert a bit to a more primitive state."

The Skeeva's growl turned to a snarl. "You're on very thin ice, Doctor," it said, warningly. The Doctor grinned inwardly. He was successfully making the Skeeva mad, which was another part of his plan. He knew from much experience that nearly every sort of being in the entire universe was a thousand times more vulnerable when angry. Anger causes defences to weaken, every single time. He'd tried explaining the process to Sadie once, but she'd vehemently denied it being possible. Pointing out the occasions where she'd let her anger get the best of her hadn't helped his cause very much, either. It'd only resulted in her not speaking to him for a while.

The Doctor stepped a bit closer, hands still stuck inside his pockets, before continuing. "On thin ice, eh?" he said. "Bit of a strange expression, don't you think? I think that's one of the reasons the English language is so confusing. It's the only language in the entire universe where skating on thin ice can land you in hot water. Complete polar opposites! And don't even get me started on the differences between American English and European English – utter insanity."

"Stop it!" The Skeeva shouted, nearly trembling with rage. "Do you think I don't know what you're doing?"

"Actually," The Doctor replied. "I'm ninety percent certain you don't have a clue what I'm doing."

"Well, you're wrong," the Skeeva answered bitterly. "I know exactly what you're doing. You're keeping me occupied out here while the moron you call a companion is inside the book looking for a way to escape." The Doctor stood silently for a moment, unsure of how to respond. This actually in no way was his plan, but he didn't think it would be wise to say so to the Skeeva. "Well?"

"Well, what?"  
"That's your plan, isn't it?"

"Oh, right, the plan," The Doctor replied simply and then fell silent, hoping to buy himself some more time. The Skeeva waited impatiently.

"Am I to assume from your silence that this is indeed your plan?"  
"One should never assume anything. You know what they say about that."

"I grow tired of your inane ramblings, Doctor," the Skeeva snarled.

"Good thing you don't travel with me then!"

At that comment, the Skeeva let out a roar and lunged at the Doctor, arms outstretched, fully prepared to rip his throat open. The Doctor dove sideways, rolling out of the Skeeva's path and towards the book that was still lying near the wall. He scooped it up in one fluid movement and ducked inside the small closet that was nearby. It was a tight fit, especially given his height, but he managed. He situated himself on the floor, back resting against the closed door. Outside, the Skeeva was yelling obscenities and emitting growls, all the while throwing itself against the door. Sadie's body was likely to have some nasty bruises after this ordeal, the Doctor thought, as he positioned the book onto his raised knees.

He flipped the book open and scanned down the page to the last thing Sadie had 'said' to him. There was more, much more that had been added since then, and his eyes quickly scanned down the page, growing steadily wider as he went.

"No!"

'Yes' appeared on the page. 'You have to.'

"Sadie, I can't. It's too risky. The implications of such an action are…well, for lack of a better term, bad!"

'Doctor, again, you have to. It's the only way.'

The Doctor sighed heavily, eyes travelling back to where he'd begun reading. He began to read again, slower this time, mulling over each word.

'Doctor, Doctor, I've found it! I've found a way to beat it!'

'…Doctor? Are you listening?'  
'Doctor!'  
'Doctor, I've found a way to get rid of the Skeeva! I really need you to listen to me!'  
'I don't know what exactly is going on out there, but this is really important. Doctor, the way to get rid of the Skeeva is to-'

"I can't do it," The Doctor mumbled, staring at the printed words. "There has to be another way."

'There is no other way,' Sadie's words appeared on the page. 'There's only one way, and this is it.' The Doctor knew she was right, as much as he hated to admit it. He knew there were very limited ways of destroying regular Skeevas, so it made perfect sense that the amount of methods would decline, given the Skeevas' survival tactic. His eyes went back once again to previous words. Despite his reservations, he knew he would have to do as Sadie said.

'Destroy the book.'


	9. Destruction

**Notes: AH! I bet you all think I fell off the face of the planet! However, I did not, I just went into lurking mode. I'm back now, so expect updates again!! Hooray!!**

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**Destruction**

The Doctor didn't want to do it, but he knew he had to. He had no other choice. Sadie seemed resigned to the fact that there was no other way and was insistently urging him just to 'get on with it'. He knew he'd have to eventually, but he couldn't help prolonging it for as long as possible. He had no idea what would happen when he actually began to destroy the book, and that unnerved him quite a bit. The unknown could be fun and exciting, but it could also scare the living daylights out of you. He sighed, the breath coming out roughly due to the still very angry Skeeva beating itself against the door that separated them. The door was beginning to splinter ever so slightly. It wouldn't be too much longer now.

"I guess this is it," he said, looking down at the book.

'I guess so,' appeared on the page a moment later.

The Doctor paused, not quite knowing what to say or do. He finally hugged the book tightly to his chest. "Sadie…"

'Quit stalling. Get on with it, and I'll see you on the outside.'

She never had been one for long goodbyes. The Doctor flipped to the first page of the book, took a page between his thumb and forefinger, and slowly tore it from the book. Immediately a howl of pain from the Skeeva coursed through the room, followed by several cries. The beating on the door ceased momentarily, but then resumed, although this time less intense. The Doctor tore two pages from the book in quick succession, crumpling them into a ball and then tossing it across the small closet with a bit of flourish. Thinking better of his action, he stretched himself across the floor to reclaim it as the Skeeva shrieked and wailed. The Doctor could tell by the sounds that the creature was moving farther from the door. He got to his feet and stuck the already torn pages into his pocket. He then tore another three pages from the book before slowly opening the battered door.

The Skeeva was crouched against the wall farthest from him, whimpering. Its breath was coming in short, ragged bursts. The skin was pale, obviously clammy, and the glowing red eyes were beginning to darken. The plan was working; the Skeeva was dying. The Doctor ripped another page from the book. The Skeeva moaned pitifully as it fell completely to the floor, writhing in pain.

"Please," it asked, the voice husky and the previous arrogance gone. "I'm begging you, please don't. No more…the pain is unbearable. It hurts too much to stay still but yet the pain is so great to move…please…"

The Doctor stood, poised to tear another several pages from the book. This was torture. He was effectively torturing this creature. The very thing he fought to prevent so many times…he was standing right here in his own ship doing that very act. How could he do such a thing?

The Skeeva's breathing became a bit smoother. The Doctor's inner turmoil was buying it some recovery time. It knew that playing up sympathy would work. That plan always worked. Oh sure, there'd be a few pages lost during the struggle, but those could be replaced.

The Doctor's fingers toyed with the corner of a page. He'd almost resigned himself to continue on when a voice broke into his thoughts.

"Doctor, please…" The Doctor's head snapped up instantly. It was Sadie's voice. "Doctor, please, it…it hurts…I didn't know it would hurt so much, please, please stop…" The Doctor was at his companion's side in just a matter of seconds. A pair of green eyes looked back up at him.

"Sadie?"

"Yes, Doctor, it's me. The Skeeva…it must have left. Please don't tear the book anymore…" The Doctor was more than a little suspicious, and it must have shown on him. "Don't you believe me?"

There was a long pause.

"I don't know."


	10. Decision

**Notes: So...um...hi? It's only been, what, a year since I updated this thing? Wow. Apologies to you all for the silence. It's just been that INSANE of a year. I must have opened this up to finish it, oh a gabillion times or more, but it just never came to be. But, here I am, and with a new chapter! FINALLY! I AM going to finish this story. I promise! Who knows, I might even write another one after this! So, yeah, if you're still out there reading, thanks for being patient. I hope it was worth it! :)**

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**Decision**

"You don't believe me?" Sadie, or who the Doctor thought was Sadie, said slowly, each word dripping with disbelief. "Why?" The Doctor frowned. He wanted to believe it was over, but centuries of experience had taught him that it was never that easy. Never. Unless…

"I…I don't know," The Doctor's resolved faltered a bit as he spoke. He was torn, utterly torn, just like the pages he'd ripped from the book just minutes before. Was this really his companion, who he could trust, or was it still the Skeeva, who he needed to destroy? Sadie stepped a bit closer, eyeing him warily. She seemed to hesitate before speaking again.

"It really is me," she said, holding her hands up in a placating gesture. "You can trust me." The Doctor looked over her carefully, looking for any sign that would tip him off to her true being. Apart from the deep purple bruises that were already beginning to form along the parts of her arms that were exposed from her shirt sleeves, he came up blank. Sadie took another cautious step forward. She seemed to be thinking, biting absently at the corner of her lip as she was wont to do in such situations. That was definitely a Sadie-trait. Maybe it was over that easily. If only he could be sure.

"Doctor…please…" she said softly, stepping closer still, hands still out. "Just take it easy. It's over." Apparently sensing that the Doctor's guard was lowering ever so slightly, Sadie closed the distance between the two, slowly lowering her arms into a more natural position. She cleared her throat, apparently hoping to dispel the tension that was still hanging within the room. "So..."

The Doctor didn't respond. He was still looking for a sign, any sign, that would clue him in as to what was going on. He just couldn't let go of that little nagging feeling that something was still wrong. She looked like Sadie, sounded like Sadie, but _was_ she Sadie? He still wasn't completely sure.

"Right," Sadie nodded, taking his lack of response in stride. "Well, why don't we just go ahead and get rid of that stupid book now? I think we'd both feel better with it gone." She reached a hand out towards the book, but the Doctor pulled it away before she ever got close. Sadie jerked her hand back, face apologetic. "I'm sorry! I just thought-"

"I'll be making the decisions around here, preferably without your input," The Doctor responded sharply, watching to take in every detail of her reaction. Sadie's eyes widened and she nodded once. Another typical thing for her. She always did that whenever he got a little…intense. Just clammed up, refusing to speak until she was sure she wouldn't get her head bitten off. If this thing really wasn't Sadie, it was doing an amazingly impeccable job of imitating her. The Doctor drummed his fingers along the spine of the book still in his hands, thoughts spinning. He froze as the answer hit him. How could he have been so dense?

"The book!"

Sadie looked confused. "The book?"

"The answer to it all! If you really are who you say you are, then the book will be changed back to normal! If you're _not_ who you say you are, then Sadie's words will still be there! Oh, why didn't I think of this before?" He flipped the book open and scanned the pages quickly. There, in large letters, was the answer he'd been looking for the whole time.

'_DESTROY IT!'_

The Doctor wasted no time. He could hear the growls coming from the Skeeva already. He grabbed a handful of the pages and ripped. He was rewarded instantly with a shriek of pain from the now-revealed imposter. He didn't stop. His sympathy was gone. He ripped until every page of the cursed book was in a pile at his feet. He tore the cover of the book in half, as well, letting it fall with a double thump to the floor.

A few feet away, curled into the smallest ball imaginable, was the un-moving body of Sadie. The Skeeva now taken care of, the Doctor had no doubt this was once again his companion. He dropped to his knees beside of her.

"Sadie?"

Her eyes fluttered once, and then opened wide. She sat up, urgency distinct in every fiber of her being. She spoke quickly, in a rough voice that showed just how harrowing this encounter had been.

"_Burn_ it."


	11. Aftermath

**Aftermath**

"Home…please."

Those had been Sadie's only words to the Doctor after the book had been burnt into cinders, and the cinders then tossed outside of the TARDIS doors to scatter throughout all time and space. Sadie had curled herself into a ball underneath a large, slightly ratty blanket after that, which had worried the Doctor. She was sore, no doubt, and exhausted in every way imaginable, so maybe it shouldn't really worry him, but it did.

The TARDIS landed in the backyard of Sadie's house, and the Doctor made his way over from the console to tell her they'd arrived.

She got to her feet without a sound, wrapped her blanket tightly around herself, and headed out the door. The Doctor followed anxiously. A small part of him was worried about any maternal responses to the state of his companion. He'd been down that route before, and he was not looking for a repeat performance. Angry mothers were the worst.

Sadie went immediately for the bathroom, closing the door behind her. The Doctor heard the small 'ping' as the lock slid home. He hovered nervously in the hallway for a few moments, until he heard the shower running. Well, he might as well make himself comfortable, since he was going to have to wait. Lucky for him, no one seemed to be home. So at least he could wait in peace and reflect. He headed for the living room, letting himself fall back onto an overstuffed chair.

Sadie stood under the shower, letting the water wash over her. She'd turned the faucet as far as it would go, meaning that the water was nearly scalding, but it felt soothing to her aching body. She rested her forehead against the cool tile, her back to the spray, and let the quiet sound of the water soothe her mind as well.

She was tired, so tired. She wanted nothing more than to crawl into bed and sleep for days. She couldn't remember ever feeling this way. Nothing she had encountered with the Doctor compared to this. Of course, all of those had been different. She had caused this problem. Maybe that was the difference.

She turned, resting her back against the tile. Much of her body was covered with rapidly-forming bruises. Soon, she'd be more purple than flesh colored. She was a mess. How would she ever explain this to anyone? She'd have to go into hiding for a while. Maybe hiding in her bed for days wasn't such a bad idea after all. How _would_ one explain this? Especially to…oh man, she hadn't even thought of her mother. She could never lie to her mother. She could try, of course, but her mother always seemed to have a sixth sense about those things.

Sadie's mind turned then to the Doctor, who was most likely oscillating nervously through her house. He would probably need rescuing from her mother's endless questioning about now. She sighed and reached for the soap.

The Doctor was finding it hard to keep still. He moved from the chair to the hallway, from the hallway to the chair, back to the hallway with a momentary stop to look at a few portraits hanging along the wall, then back to the chair yet again. He perked up when he heard the shower turn off. He hated waiting, especially waiting like this, so the thought of it coming to an end was wonderful.

Four minutes and twenty-six seconds later, the door opened and Sadie made her way out. She paused briefly, looking around for her mother.

"She isn't here," the Doctor stated, answering her wordless question. Sadie nodded. She crossed the room in a few strides and let herself fall back onto the couch, her eyes closed. The two of them sat in silence for a few moments before Sadie muttered something so softly that the Doctor couldn't make it out. He leaned forward, resting his elbows on his knees.

"What did you say? I couldn't hear it."

"'m sorry," Sadie mumbled again, looking up to meet his eyes once before dropping her gaze to the floor. She took a deep breath as if she was going to continue, but then stopped.

"You're sorry? For?" the Doctor questioned, frowning. Sadie sat up, taking a shaky breath.

"For everything! For being so stupid and for bringing that _thing_ into the TARDIS and for putting us in danger and then for being stupid again and not being able to figure out how to get rid of that creature and just...for everything. It's all my fault, and I'm just really sorry. I've been thinking a lot, and I'd completely understand if you'd want me to stop traveling with you because of all this and-"

"Sadie, breathe." She did as told, taking in a few much needed breaths. "Now. Nothing has changed. I still want you to come with me, as long as that's what you want."

"I do!" Sadie met his eyes once again. "More than anything, I do, but I just thought…y'know…since it was in the TARDIS and that's your ship! I mean, I could have completely ruined your whole lifestyle and-"

"There have been worse things happen to the TARDIS, believe me," the Doctor interrupted.

"Really?"  
"Really. Plus, it'd take a lot more than a little old Skeeva to stop me. I _am_ the Doctor, after all." Sadie grinned. "There now, that's much better. See, I told you my ego was good for something."

"I'll concede that it was good this one time, and this one time only. The other times not so much. But I suppose we'll have plenty of time to argue the point, won't we?"

"All the time in the world."

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**Hooray! I finally finished it! THANK YOU to all those who stuck with this story - you guys are awesome, plain and simple. I've gotten a few ideas for more Doctor/Sadie adventures, so be on the lookout for those. :)**


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